Characterization of Electroplated Cu Thin Films on Electron-Beam-Evaporated Cu Seed Layers

Cu and Ti of 20 nm, respectively, were deposited onto p-type Si(100) substrate for use as a seed layer by using electron-beam evaporation. Potentiostatic electrodeposition was carried out using the three-terminal method, with an Ag/AgCl reference electrode, a platinum plate as a counter electrode and the seed layer as a working electrode. The plating electrolyte was composed of CuSO4, H2SO4, HCl and three organic additives (accelerator, suppressor and leveler). The amounts of the additives were changed. The resistivity of the electroplated Cu lms was measured with a four-point probe and the physical properties were investigated using eld emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray di raction (XRD) and Xray photoelectron spectroscopy (XPS). The increases in the plating concentrations of the organic additives (the increases in the accelerator, the suppressor and the leveler for the high sample were +2, +0.5 and +1 mL/L, respectively as compared with the low sample) led to a predominant Cu (111) texture, an increased lm density and a decreased electrical resistivity of the electroplated Cu lm.